<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<p>整数1：<input id="num1" type="text"></p>
<p>整数2：<input id="num2" type="text"></p>
<p>
    <input type="button" value="相加" onclick="calc(add)">
    <input type="button" value="相减" onclick="calc(sub)">
    <input type="button" value="相乘" onclick="calc(mul)">
    <input type="button" value="相除" onclick="calc(div)">
</p>
<>结果：<input id="result" type="text" readonly></p>
<script>
    function calc(func){
        var result = document.getElementById('result');
        var num1 = parseInt(document.getElementById('num1').value);
        var num2 = parseInt(document.getElementById('num2').value);
        if (isNaN(num1) || isNaN(num2)) {
            alert('请输入数字');
            return false;
        }
        result.value = func(num1,num2);
    }
    </script>
<script>
     function add(num1,num2) {
         return num1 + num2;
     }
     function sub(num1,num2){
         return num1 - num2;
     }
     function mul(num1,num2) {
         return num1 * num2;
     }
     function div(num1,num2) {
         if (num2 === 0){
             alert('除数不能为0');
             return '';
         }
         return num1/num2;
     }
</script>
</body>
</html>